The NXP pcf8523 supports two different xtal load capacitance
- 7000fF (7pF) HW default
- 12500fF (12.5pF) Minimum power consumption, driver default
To obtain a precise RTC the pcf8523 must be configured
with the correct capacitance load of the xtal.
Add a property to specify the xtal capacitance load.
The default value matches that of the current Linux driver.
With a dedicated binding remove the entry in rtc.txt
Signed-off-by: Søren Andersen <s...@skov.dk>
Signed-off-by: Sam Ravnborg <s...@ravnborg.org>
Reviewed-by: Rob Herring <r...@kernel.org>
Cc: Alessandro Zummo <a.zu...@towertech.it>
Cc: Alexandre Belloni <alexandre.bell...@bootlin.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
---
Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt | 18 ++++++++++++++++++
Documentation/devicetree/bindings/rtc/rtc.txt | 1 -
2 files changed, 18 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
new file mode 100644
index 000000000000..0b1080c60f63
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/nxp,pcf8523.txt
@@ -0,0 +1,18 @@
+* NXP PCF8523 Real Time Clock
+
+Required properties:
+- compatible: Should contain "nxp,pcf8523".
+- reg: I2C address for chip.
+
+Optional property:
+- quartz-load-femtofarads: The capacitive load of the quartz(x-tal),
+ expressed in femto Farad (fF). Valid values are 7000 and 12500.
+ Default value (if no value is specified) is 12500fF.
+
+Example:
+
+pcf8523: rtc@68 {
+ compatible = "nxp,pcf8523";
+ reg = <0x68>;
+ quartz-load-femtofarads = <7000>;
+};
diff --git a/Documentation/devicetree/bindings/rtc/rtc.txt
b/Documentation/devicetree/bindings/rtc/rtc.txt
index 41eb335ea816..6d726a801d21 100644
--- a/Documentation/devicetree/bindings/rtc/rtc.txt
+++ b/Documentation/devicetree/bindings/rtc/rtc.txt
@@ -55,7 +55,6 @@ isil,isl12022 Intersil ISL12022 Real-time Clock
microcrystal,rv3029 Real Time Clock Module with I2C-Bus
nxp,pcf2127 Real-time clock
nxp,pcf2129 Real-time clock
-nxp,pcf8523 Real-time Clock
nxp,pcf8563 Real-time clock/calendar
nxp,pcf85063 Tiny Real-Time Clock
pericom,pt7c4338 Real-time Clock Module
--
2.12.0
